This invention relates to a safety device for a fastener installation tool provided with collection means for collecting parts of fasteners which are broken off during installation of the fastener.
Fastener installation tools including collection means are known, for example as described in GB 2372475B. The tools may be provided with a vacuum extraction facility whereby broken-off parts, i.e. stems, are ejected into the collection means during normal operation of the tool. The collection means may be removable to allow the tool operator to empty the broken-off parts, i.e. stems, from the collection means. Installation tools having removable collection means may include a safety shutter, which is actuated when the collection means is removed from the tool. The safety shutter when actuated provides a fixed barrier normal to the path of the stems, and prevents stems from being ejected from the tool without the collection means being in place, which could cause injury to the operator.
However, a problem with the use of such a safety shutter is that the stems may jam in the installation tool. Continued use of the installation tool is possible even when the collection means has been removed, with the safety shutter acting to keep the broken-off fastener parts within the tool. Such continued use causes damage to the safety shutter, and causes stems to build up within the piston, necessitating partial dismantling of the tool to clear the build up.
The applicant's co-pending application patent application GB 0702792.3 discloses an installation tool having a shutter urged closed by resilient means. If the tool is operated with the collector bottle disconnected, broken-off fastener stems collect within the tool. Once a sufficient number of stems have collected within the tool, the resilient means are overcome to allow the shutter to open and allows stems to be ejected from the tool in a controlled manner.
It is an aim of the present invention to provide a simple means for preventing broken-off fastener stems from being ejected from the rear of an installation tool whilst the collector bottle is not attached, and to prevent the jamming of broken off fastener stems within the tool.
Accordingly, the present invention provides, in one aspect, a fastener installation tool for installing fasteners of the type in which a part of the fastener is broken off during the installation process, which fastener installation tool is provided with a trigger, wherein depression of the trigger causes actuation of a main operating valve thereby to install a fastener, and collection means for collecting broken-off fastener parts during operation of the tool, the collection means being removably connected to the tool; the tool being further provided with disabling means which are actuable to prevent operation of the main operating valve thereby to prevent use of the tool to install a fastener, the arrangement being such that when the collection means is disconnected from the tool, the disabling means are actuated.
The present invention provides a fastener installation tool wherein the tool is disabled when the collector bottle is unattached. As the tool cannot be used when the collector bottle is not attached, the risk of injury or damage caused by broken off stems being ejected from the tool is prevented. Furthermore, broken-off stems cannot build up within the tool, thereby preventing the potential jamming of stems necessitating dismantling of the tool.
The disabling means preferably acts to disable the tool by preventing operation of the tool trigger. The disabling means may additionally act to disable the vacuum extraction facility in addition to the tool trigger and main operating valve.
The disabling means may comprise a valve, which may be connected in series with the tool trigger and the main operating valve. Alternatively, the valve could be positioned between the main operating valve and the air inlet through which compressed air is supplied to the tool.
The valve may be maintained in an open position by a positive pressure signal, wherein removal of the pressure signal causes the valve to change to a closed position. In an alternative embodiment, the valve could be maintained in a closed position by a positive pressure signal, wherein removal of the pressure signal causes the valve to change to an open position.
In an alternative embodiment, the disabling means may include a chamber which is supplied with air at first rate when the collection means is connected to the tool, wherein depression of the tool trigger causes evacuation of the chamber thereby causing actuation of the main operating valve, and wherein the chamber is supplied with air at a second rate, the second rate being higher than the first, such that when the collection means is disconnected, the air supplied to the chamber is greater than that which can be evacuated on depression of the tool trigger, thereby preventing actuation of the main operating valve. The disabling means of this embodiment may further include at least two valves which are open when the collection means is disconnected from the tool, and closed when the collection means is connected to the tool.
The chamber is preferably positioned between the tool trigger and the main operating valve.